Early Results from Early Results from SWIFT's BAT AGN SWIFT's BAT AGN

Survey: XMM Follow-up Survey: XMM Follow-up Observations for 22 BAT Observations for 22 BAT

AGNsAGNsLisa WinterLisa Winter (Grad Student at UMD)

Richard Mushotzky (GSFC), Jack Tueller (GSFC), Craig Markwardt (GSFC), Christopher Reynolds (UMD)

SWIFT BAT Survey

• The Swift BAT is an 'all sky' instrument- covering ~20% of the sky at any one time and ~ 50% of the sky each day when not triggering on GRBs

• Sensitive in the 15-150 keV band

• Random nature of GRBs leads to relatively uniform sky coverage for BAT- sensitivity 1-3 mC, angular accuracy ~1.7'

• Extensive follow-up of sources by the two other telescopes on SWIFT (UVOT and XRT) with relatively short exposures

‘Unbiased’ Survey

• All previous AGN surveys were biased (wrt obscuration)

• Much larger sample than HEAO-1 (and Integral)-1st sensitive all sky hard x-ray survey in 28 years !

• BAT data provides first large unbiased sample of host galaxy properties

• Direct comparison with z~1 Chandra and XMM surveys* Distribution of N(H) values* Luminosity function* Log N-Log S

*necessary for modeling x-ray background

SWIFT BAT Survey Compared to Other X-ray

Surveys

Brandt & Hasinger 05

Sy2Sy1

I-mag calculated from 2MASS K-mag assuming K-I = 2

(Ferraras et al. 99)

+1

0-1

Log(FX/FI)

-2

Follow-up Observations

• 22 10 ks XMM observations from 26 proposed sources

• Sources selected: Detected with BAT as a

5 sigma or higher detection

Optical counterpart clearly seen in DSS/2MASS images

No previous X-ray spectrum

X-ray contours from SWIFT’s XRT

X-ray Properties of the Sources

XMM follow-up sources:

- Range of fluxes (FX(0.3-10 keV)) from 1.6x10-12 to 3.0x10-11 erg/s cm2

- 8 “unabsorbed” sources (nH < 1021)

- 14 “absorbed” sources, 5 of which are “Compton thick”Log nH (cm-2)

Compton thick

BAT AGNXMM Follow-up

Log

FX (

10-1

00 k

eV)

Spectral Energy Distributions

• Simultaneous XMM OM data in U, UVW1, UVM2, and UVW2 filters

• In addition to the OM data, nearly all of the sources will have SWIFT UVOT data available.

BA

T 1

0-10

0 ke

V

2-10

keV

0.5-

2 ke

V

XMM OM

Sy2Sy1

Characteristic XMM X-ray Spectra

Unabsorbed

ESO 362-G018

Mkn 352

nH = 1023 cm-2

Fe K eqw = 450 eV

NGC 1142

CGCG 041-020

nH = 1023 cm-2

Compton thickFe K eqw = 260 eV

Fe K-alpha lines and Compton thick sources

•Many of the Compton thick sources in the BAT sample have Fe EW <500 eV •For example Mkn 417 has Fe EW ~70 eV and yet is clearly Compton thick •It is not yet clear what this means

BAT

BAT

BAT + XRT/XMM spectra

• We can check variability between XRT and XMM obs.

0.3 - 2 keV

2 - 10 keV

12 of 20 sources with XRT and XMM spectra are variable by 20%

or more

~ 100 days

ESO 362-G018

Summary

• With XMM and XRT data, we are compiling SEDs for the BAT AGN sample

• With XRT and other (XMM, Chandra, etc.) X-ray observations we are collecting information on source X-ray variability.

• Interesting results: 11/14 absorbed sources show weak soft

emission Compton thick sources with small Fe K

equivalent widths (as low as 70 eV for Mrk 417)

Future Work

• XMM Proposal for ~ 25 absorbed XRT sources/sources with no X-ray spectrum

• Working to obtain optical spectra for sources with none published/publicly available (roughly 15% of the current BAT AGNs have no optical spectra available)

• Analysis of the Swift XRT spectra